I'm not sure about catch but in the Sinoh dex you can see 150 Pokemon
no but you can see it from Cynthia's gramma
upgrade to the national dex and see and catch every Pokemon
(in Pokemon Pearl?) can catch it in snowpoint cave (in snowpoint) you have to go all the way down then you will see regice but you need to have beaten the elite 4
You cannot catch bulbasaur in diamond and pearl. If you have firered or leafgreen can set 6 Pokemon free in pal park and catch them there.
To finish the sinnoh dex (Pokemon platinum's,diamond, and pearl dex) you just need to see every Pokemon not catch every Pokemon.
You can't catch it, but you can see it being used by a Trainer on Route 224 and then you can trade for it.
Unlike in other games you just have to see the Pokemon not catch them but when professor oak gives you the natinal pokedex you have to catch the Pokemon
You Have to atleast see all the Pokemon or catch them then go to the professer and he will gave you the National Pokedex
You can't catch it in Pokemon Platinum but you can get it in Pokemon Pearl in Eterna Forest at night or in the Lost Tower.
1) catch a magicarp with an old rod 2) evolve it. or catch 130 "gyrados" with a super rod at various locations.
You can't catch Dialga in Pokemon Pearl; however, you can see it. Go to Celestic Town, and go to the northern house. The woman inside shows you a picture of Dialga. This counts as being "seen" in your Pokedex. In Pokemon Diamond, it will be a picture of Palkia.
The good news is that you don't have to catch all the Pokemon, but you only have to see all the sinnoh Pokemon to get the national dex:)